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United States Patent | 5,579,676 |
Wilke | December 3, 1996 |
A hydraulic fluid-loss control valve for preventing uncontrolled load movement in the event of a fluid loss such as from the bursting of a hose and further for allowing an operator to move the load in a controlled way despite the fluid loss. The control valve is situated between a conventional main spool valve and a piston/cylinder hydraulic actuator which powers the load. The control valve has a spool sliding reciprocally in a bore. Grooves and lands on the spool combine with passages in the control valve body to provide alternate fluid paths between a pump and the actuator and between the actuator and a reservoir. Fluid can flow from a controlled chamber of the actuator only when the spool is in a position which provides a fluid path. A passage within the spool provides fluid communication between an input fluid flow and a chamber at one end of the spool. A second passage within the spool provides fluid communication between an actuator chamber and a chamber at the other end of the spool. The position of the spool is determined by the balancing of the opposing end-chamber pressures, which is under the control of the operator.
Inventors: | Wilke; Raud A. (Dousman, WI) |
Assignee: | HUSCO International, Inc. (Waukesha, WI) |
Appl. No.: | 502026 |
Filed: | July 13, 1995 |
Current U.S. Class: | 91/420; 91/421; 91/436; 91/446; 137/106 |
Intern'l Class: | F15B 011/08; F15B 013/04 |
Field of Search: | 91/420,421,436,517,444,445,446,447,448 137/106 |
3685540 | Aug., 1972 | Wilke | 137/596. |
4446890 | May., 1984 | Simpson, Jr. | 91/421. |
5036750 | Aug., 1991 | Katayama | 91/445. |
5076143 | Dec., 1991 | Ogawa | 91/420. |
5113894 | May., 1992 | Yoshida | 137/106. |
5347811 | Sep., 1994 | Hasegawa et al. | 91/517. |
5400816 | Mar., 1995 | Gerstenberger | 91/447. |